With the rapid development of the industry, the problems of gradual exhaustion of fossil fuels and greenhouse gas emission are increasingly concerned around the world, and stable supply of energy resources apparently becomes a worldwide major topic. Compared with conventional coal-fired, gas-fired, or nuclear power generation, a solar cell directly converts solar energy into electric energy by a photoelectric or thermoelectric conversion effect without producing following greenhouse gases or polluting gases, such as carbon dioxide, nitrogen oxides, and sulfur oxides, thereby reducing dependence on fossil fuels, and providing a safe and independent power source.
In many solar cell technologies, radiant light of the sun converted by a solar cell material becomes a usable power source. Taking a crystalline silicon solar cell as an example, the crystalline silicon solar cell has photoelectric conversion efficiency of 12% to 20%, and the solar cells designed with different crystal materials have different photoelectric characteristics. Generally, the conversion efficiency of monocrystalline silicon or polycrystalline solar cells is approximately 14% or 16%, so duration of service is longer, but the power generation cost of the monocrystalline silicon or the polycrystalline solar cells is high. Therefore, subsidies from government are needed and this kind of solar cells are only applicable to power plants or traffic light signals.
In addition, besides the above silicon materials, the solar cells may further be made of other materials, for example, III-V compound semiconductor materials such as Indium Gallium Arsenide (InGaAs) and Gallium Arsenide (GaAs). Different from the crystalline silicon solar energy technology, the solar cells made of the III-V compound semiconductor material can absorb energy of wider solar spectrum, thus achieving the highest photoelectric conversion efficiency up to almost above 60% to 70%.
However, the manufacturing cost and the price of the solar cell made of III-V compound semiconductor material are also the highest among all kinds of solar cells. Therefore, in order to decrease a use of the solar cells and reduce power generation cost, a solar collector is equipped to reduce a light absorption area. However, the cost is compensated only when the solar collectors are required to be installed in a large area, thus incurring application inconvenience, and limiting application of the solar cells. Therefore, how to effectively reduce the power generation cost of the solar cell is actually one major topic people skilled in the art eagerly are required to solve currently.